I've not run it with the cover on, heck I've not run it with RAM installed, so it's just the default fan speed. Still it's basically in audible from three feet away. Well, a bit of a rushing air sound, but the fans are cranked up way higher than needed. I think it's going to be pretty much silent once I turn them down.

I was worried for a bit when I got into the UEFI (BIOS), I couldn't turn the fan down below 60% duty cycle, and the CPU fan that is now handling they case was vary audible even at that speed.

But I installed Windows 8.1 (without a key for now, still not sure if I'll buy it) and added the Asus utilities. OK, the Fan Xpert 2 is awesome! It mapped the fan's duty cycle vs. cooling and let me slow them down a lot more than the UEFI settings would allow. Now everything is peaceful.

I'm also looking at slowing down the Bitfenix case fan i bought for my new rig. There is a dial on the case itself, but i think the fan is still running louder/faster than it needs to. Mind you, i'm using the top fan port so it's also possible the noise is just more audible as in the past i've used front and back fan ports.I'm going to play around with the location and in doing so, close off the top fan port with (non glued) acoustic material as well.Other than that, i have a fairly silent system.